Effect of arsenic trioxide on growth of a heterologous graft model for human breast cancer in nude mice

Objective To study the inhibitory effect of arsenic trioxide(AS2O3)on the tumor growth of breast cancer line MDA-MB-435s implanted subcutaneously in nude mice and its mechanism.Methods BALB/C-nu/nu nude mice were subcutaneously injected with MDA-MB-435s breast cancer cells that are ER-positive,and treated with intraperitoneal injection of AS2O3 and DDP in different concentrations.The implanted tumor was weighed,and tumor inhibition rates were calculated.The expression of PTEN and Caspase-7 induced by AS2 03 were examined by immunohistochemical method.Results The growth of implanted tumor was markedly inhibited with DDP,low dose and high dose AS2O3,and the inhibitory rates were 48.68%,32.80%,66.67%respectively.The immunohisto chemical staining showed that the number of PTEN and Caspase-7 protein increased markedly(P＜0.05).Conclu sions AS2O3 inhibits the growth of human breast cancer cell implanted tumor.The molecular mechanism of AS2O3 on induction of apoptosis of breast cancer cells may be throush increasing the expression of PrrEN and Caspase-7(P ＜0.05). Key words: breast cancer; AS2O3; nude mice; PTEN; Caspase-7